Duplicating machines



Jan. 2@, 1959 --A. G. R. GATES 2,869,45fi

DUPLICATING MACHINES Filed Feb. 1, 1956 4 Sheets-Sheet l 1mm 195 A. G. R. GATES 2,8fi9545g DUPLICATING MACHINES Filed Feb. 1, 1956 4 Sheets-Sheet 2 4" Attorney;

Jan. 20, 1959 A. G. R. GATES 2,869,458 DUPLICATING MACHINES Filed Feb. 1, 1956 4 Sheets-$heet 3 m bg ttorney;

Jan. 20 1959 A. G. R. GATES 2,869,458 DUPLICATING MACHINES Filed Feb. 1, 1956 4 Sheets-Sheet 4 f N [nvenir l 5 f 1 A ttorne vs United States Patentofiice 2,869,458 Patented Jan. 20, 1959 DUPLICATING MACHINES Albert G. R. Gates, London, England, assignor to Gestetner Limited, London, England, a British company Application February 1, 1956, Serial No. 562,903

Claims priority, application Great Britain December 13, 1955 11 Claims. (Cl. 101-247) This invention relates to duplicating machines and more particularly to twin cylinder stencil duplicating machines of the type in which a stencil carrier assembly travels around a top and bottom cylinder and sheets of paper are fed in succession between the bottom cylinder and a pressure roller which presses the sheets against a stencil carried by the said assembly, the sheets being delivered from between the bottom cylinder and the pressure roller to a trap or platform to build up a stack of copies thereon. it should be clearly understood, however, that the invention may be used not merely on twin cylinder stencil duplicating machines but also, for instance, on single drum stencil duplicating machines and on hectographic duplicating machines.

In twin cylinder stencil duplicating machines of the aforesaid type the pressure roller is periodically moved towards the bottom cylinder, so as to apply printing pressure to the sheets of paper, and away from the bottom cylinder, so as to release said pressure and so as to clear projections on the stencil carrier assembly. This printing pressure has hitherto been effected by means including springs with the result that at high speed the pressure roller, on initially contacting the bottom cylinder, is liable to rebound away therefrom whereby the head of the stencil is subjected to unnecessary strains.

The object of the present invention is to provide improved means for applying the printing pressure whereby said rebound which may occur upon initial contact of the pressure roller with the bottom cylinder may be substantially reduced.

According to the invention there is provided a duplicating machine comprising a pressure roller carried by a rotatably mounted support, a torsion bar one of whose ends is secured to the support, and means for periodically oscillating the other end of thetorsion bar, the arrangement being such that movement of the said other end of the torsion bar in one direction brings the pressure roller into contact with a cylinder of the machine and thereafter subjects the torsion bar to torsion whereby the pressure roller eXerts printing pressure, and movement of the said other end of the torsion bar in the opposite direction releases said printing pressure and moves the pressure roller away from the cylinder.

The support is preferably a sleeve within which the torsion bar is mounted, the said other end of the torsion bar extending outwardly of the sleeve and being secured to an oscillatable lever.

Means may be provided for subjecting the torsion bar to an'initial torsion and for adjusting the amount of initial torsion applied. The said adjusting means may comprise a plate secured to the torsion bar and means for securing the plate to the lever so that the relative positions of the plate and lever may be varied.

' Preferably the lever is periodically oscillated by camoperated means.

The invention is illustrated, by way of example, in the accompanying drawings in which:

Figure 1 is a perspective view of a frame for the pressure roller of a duplicating machine,

Figure 2 is a sectional elevation of the frame shown in Figure 1,

Figures 3, 5 and 7 are end views of a part of the frame of Figures 1 and 2 showing the components of the frame in various positions, and

Figures 4 and 6 are diagrammatic views showing positions of the pressure roller and a cylinder of the machine when the said components are in the positions shown in Figure 3 and in Figures 4 and 7 respectively.

Referring to the drawings, a duplicating machine comprises a pressure roller 1 adapted to be moved towards and away from a cylinder 2 which may be the bottom cylinder of a twin cylinder stencil duplicating machine. The spindle 1' of the pressure roller 1 is mounted in grooves 3 formed in a pair of spaced supports 4 extending outwardly of a frame 5. The spindle 1 is retained in position in the grooves 3 by members 6 which are pivotally mounted at 7 on the supports 4 and which are downwardly urged (by springs not shown) so as to retain the spindle in position. Finger pieces 8 are provided on the member 6 to enable the latter to be raised and the pressure roller to be withdrawn.

The frame 5 is secured to a sleeve 9 whose opposite ends are rotatably mounted in the frame 10 of the machine. Within the sleeve 9 is mounted a torsion bar 11 one end of which is pinned to the sleeve 9 at 12. The other end of the torsion bar 11 is pinned at 13 to a bush 14 welded to an elongated plate 15. The latter is secured to a lever 16 by means of a bolt 17 having a projection 18 adapted to bear against the sides of an elongated hole 19 in the plate 15. The bolt 17 and projection 18 are eccentric with respect to each other whereby rotation of the bolt 17 alters the relative positions of the plate 15 and lever 16.

The lever 16 is formed with a curved groove 20 which receives a pin 21 outstanding from a bracket 22. The latter is welded to a bush 23 which is keyed to the sleeve 9. The diameter of the groove 20 is greater than that of the pin 21 whereby limited relative movement can occur between the lever 16 and the sleeve 9. The torsion bar is maintained at an initial torsion by virtue of the pin 21 normally bearing against the right hand edge of the groove 20. This torsion may be altered as required by adjustment of the bolt 17.

The lever 16 is also provided adjacent its upper end with rollers 24, 25, the roller 25 co-operating with cam means (not shown) for lowering the frame and pressure roller, and the roller 24 co-operating with a curved end 26 of a slide 27.

The slide 27 is provided with an elongated slot 28 and with a roller 29. A rotatably mounted shaft 30 passes through the slot 28 and carries a cam 31 adapted to co-operate with the roller 29. When the parts are in the position shown in Figure 3, the roller 29 is in contact with a low portion 32 of the cam 31 and the pressure roller 1 is out of contact with the cylinder 2, as illustrated diagrammatically in Figure 4.

In operation, the cam 31 rotates anticlockwise and in so doing will act on the roller 29 so as to push the slide 27 upwardly, as indicated by the arrow 33. The lever 16 is therefore moved clockwise and hence the pressure roller 1 is raised until it contacts the cylinder 2 (as shown in Figure 6). In Figure 5, in which the parts are shown in the positions they assume when the pressure roller has just contacted the cylinder 2, it will be noted that the roller 29 has not yet reached the high portion 34 of the cam 31 and that the pin 21 is (as in the Figure 3 position of the parts) in co tact with the right hand side of the groove 20.

Further anticlockwise rotation of the cam 31 causes the high portion 34 of the cam 31 to cooperate with the roller 29, whereby the slide 27 is moved upwardly a small additional distance (see Figure 7). The pressure roller 1 cannot be raised further since it is in contact with the cylinder 2. The raising of the slide 27 through the said small additional distance will, however, cause some further clockwise movement of the lever 16 and hence some twisting of the torsion bar. Printing pressure will therefore be applied to the pressure roller 1, and will continue to be applied so long as the high portion 34 of the cam 31 is in contact with the roller 29.

Still further anticlockwise rotation of the cam 31 will cause the printing pressure to be released from the pressure roller and the latter will then return to the position illustrated in Figure 4.

I claim:

1. A duplicating machine comprising a cylinder, 2. rotatably mounted support, a pressure roller carried by said support and movable towards and away from said cylinder so as to apply and to release printing pressure, a torsion bar one of whose ends is secured to the support, means for subjecting said torsion bar to an initial torsion, means for adjusting the amount of initial torsion applied, and means for periodically rotating said other end of said torsion bar in one direction to bring said pressure roller into contact with said cylinder and thereafter to subject said torsion bar further to torsion, whereby said pressure roller exerts printing pressure, and for subsequently rotating said other end of said torsion bar in the other direction to release said printing pressure and thereafter to move said pressure roller away from said cylinder.

2. A duplicating machine comprising a cylinder, a rotatably mounted sleeve, a pressure roller carried by said sleeve and movable towards and away from said cylinder so as respectively to apply and to release printing pressure, a torsion bar mounted within said sleeve and having one end secured thereto, means for subjecting said torsion bar to an initial torsion, means for adjusting the amount of initial torsion applied, a lever secured to said other end of said torsion bar, said other end of said torsion bar extending outwardly of said sleeve, and means for periodically rotating said lever in one direction to bring said pressure roller into contact with said cylinder and thereafter to subject said torsion bar to further torsion, whereby said pressure roller exerts printing pressure, and for said lever in the other direction to release said printing pressure and thereafter to move said pressure roller away from said cylinder.

3. A duplicating machine comprising a cylinder, a rotatably mounted sleeve, a pressure roller carried by said sleeve and movable towards and away from said cylinder so as respectively to apply and to release printing pressure, a torsion bar mounted within said sleeve and having one end secured thereto, means for subjecting said torsion bar to an initial torsion, a plate secured to the other end of said torsion bar, said other end extending outwardly of said sleeve, a lever secured to said plate, means for adjusting the relative positions of said plate and said lever so as to adjust the amount of initial torsion applied, and means for periodically rotating said lever in one direction to bring said pressure roller into contact with said cylinder and thereafter to subject said torsion bar to further torsion, whereby said pressure roller exerts printing pressure, and for subsequently rotating said lever in the other direction to release said printing pressure and thereafter to move said pressure roller away from said cylinder.

4. A duplicating machine comprising a cylinder, a rotatably mounted sleeve, a pressure roller carried by said sleeve and movable towards and away from said cylinder so as respectively to apply and to release printing pressure, a torsion bar mounted within said sleeve and having one end secured thereto, means for subjecting said torsion bar to an initial torsion, a slotted plate secured to the other end of said torsion bar,said other end extending outwardly of said sleeve, a lever, a bolt connecting said plate and said lever together, said bolt having a projection eccentric with respect thereto and adapted to bear against the sides of said slot in said plate, rotation of said bolt altering said relative positions of said plate and said lever whereby to adjust the amount of initial torsion applied, and means for periodically rotating said lever in one direction to bring said pressure roller into contact with said cylinder and thereafter to subject said torsion bar to further torsion, whereby said pressure roller exerts printing pressure, and for subsequently rotating said lever in the other direction to release said printing pressure and thereafter to move said pressure roller away from said cylinder.

5. A duplicating machine comprising a cylinder, a rotatably mounted sleeve, a pressure roller carried by said sleeve and movable towards and away from said cylinder so as respectively to apply and to release printing pressure, a torsion bar mounted within said sleeve and having one end secured thereto, a lever secured to the other end of said torsion bar, said other end of said torsion bar extending outwardly of said sleeve, a pin and groove connection between said lever and said sleeve, the width of said groove being greater than that of said pin, and means for periodically rotating said lever in one direction to bring said pressure roller into contact with said cylinder and thereafter to subject said torsion bar to further torsion, whereby said pressure roller exerts printing pressure, and for subsequently rotating said lever in the other direction to release said printing pressure and thereafter to move said pressure roller away from the said cylinder.

6. A duplicating machine according to claim 5 in which said groove is formed in said lever and in which said pin projects outwardly of a bracket secured to said sleeve.

7. A duplicating machine comprising a cylinder, a rotatably mounted sleeve, a pressure roller carried by said sleeve and movable towards and away from said cylinder so as respectively to apply and to release printing pressure, a torsion bar mounted within said sleeve and having one end secured thereto, a plate secured to the other end of said torsion bar, said other end extending outwardly of said sleeve, a lever adjustably secured to said plate and adapted to apply initial torsion to said torsion bar, a pin and groove connection between said lever and said sleeve, said width of said groove being greater than that of said pin, and means for periodically rotating said lever in one direction to bring said pressure roller into contact with said cylinder and thereafter to subject said torsion bar to further torsion, whereby said pressure roller exerts printing pressure, and for subsequently rotating said lever in the other direction to release said printing pressure and thereafter to move said pressure roller away from said cylinder.

8. A duplicating machine comprising a cylinder, a rotatably mounted sleeve, a pressure roller carried by said sleeve and movable towards and away from said cylinder so as respectively to apply and to release printing pressure, a torsion bar mounted within said sleeve and having one end secured thereto, a slotted plate secured to the other end of said torsion bar, said other end extending outwardly of said sleeve, a lever, a pin and groove connection between said lever and said sleeve, the width of said groove being greater than that of the pin, a bolt connecting said plate and said lever together, said bolt having a projection eccentric with respect thereto and adapted to bear against the sides of said slot in said plate, rotation of said bolt altering said relative positions of said plate and said lever, and means for periodically rotating said lever in one direction to bring said pressure roller into contact with said cylinder and thereafter to subject said torsion bar to torsion, whereby said pressureroller exerts printing pressure, and for subsequently rotating said lever in the other direction to release said printing pressure and thereafter to move said pressure roller away from said cylinder.

9. A duplicating machine according to claim 8 in which said groove is formed in said lever and in which said pin projects outwardly of a bracket secured to said sleeve.

10. A duplicating machine comprising a cylinder, a rotatably mounted sleeve, a pressure roller carried by the sleeve and movable towards and away from the cylinder so as respectively to apply and to release printing pressure, a torsion bar mounted within the sleeve and having one end secured thereto, means for subjecting the torsion bar to an initial tension, means for adjusting the amount of initial tension applied, an oscillatable lever secured to the other end of the torsion bar, said other end of the torsion bar extending outwardly of the sleeve, a slide, a roller carried by said slide, a rotatably mounted cam contacting said roller so that rotation of the cam effects reciprocation of the slide, and means secured to the lever at a point remote from the torsion bar, the slide having an edge cooperating with said means whereby reciprocation of the slide effects oscillation of the lever so as to cause the pressure roller to apply and to release said printing pressure.

11. A duplicating machine comprising a cylinder, a rotatably mounted sleeve, a pressure roller carried by the sleeve and movable towards and away from the cylinder so as respectively to apply and to release printing pressure, a torsion bar mounted within the sleeve and having one end secured thereto, means for subjecting the torsion bar to an initial tension, a slotted plate secured to the other end of the torsion bar, said other end extending outwardly of the sleeve, an oscillatable lever, a bolt connecting the plate and lever together, said bolt having a projection eccentric with respect thereto and adapted to bear against the sides of the slot in the plate, rotation of said bolt altering the relative positions of the plate and lever whereby to adjust the amount of initial tension applied, a slide, a roller carried by said slide, a rotatably mounted cam contacting said roller so that rotation of the cam effects reciprocation of the slide, and means secured to the lever at a point remote from the torsion bar, the slide having an edge cooperating with said means whereby reciprocation of the slide elfects oscillation of the lever so as to cause the pressure roller to apply and to release said printing pressure.

References Cited in the file of this patent UNITED STATES PATENTS 2,198,728 Horii Apr. 30, 1940 2,518,878 Gerla'ch Aug. 15, 1950 FOREIGN PATENTS 337,832 Italy Mar. 13, 1936 

